Category: Scoring

Scoring is due to combination of two distinct activities: First, lubrication failure in
the contact region and second, establishment of metal to metal contact. Later
on, welding and tearing action resulting from metallic contact removes the metal
rapidly and continuously so far the load, speed and oil temperature remain at the
same level. The scoring is classified into initial, moderate and destructive.

Types of scoring:

Initial scoring

Moderate scoring

Destructive scoring

Initial scoring

Initial scoring occurs at the high spots left by previous machining. Lubrication
failure at these spots leads to initial scoring or scuffing .Once these high spots are removed, the stress comes down as the load is distributed over a larger area. The scoring will then stop if the load, speed and temperature of oil remain unchanged or reduced. Initial scoring is non-progressive and has corrective action associated with it.

Initial scoring

Moderate scoring

After initial scoring if the load, speed or oil temperature increases, the scoring will
spread over to a larger area. The Scoring progresses at tolerable rate. This is
called moderate scoring.

Moderate scoring

Destructive scoring

After the initial scoring, if the load, speed or oil temperature increases
appreciably, then severe scoring sets in with heavy metal torn regions spreading
quickly throughout . Scoring is normally predominant over the pitch line region since elastohydrodynamic lubrication is the least at that region. In dry running, surfaces may seize.